tileplot: Plot a spatial mosaic from irregular 2D points

In latticeExtra: Extra Graphical Utilities Based on Lattice

Description

Represents an irregular set of (x, y) points with a color covariate. Polygons are drawn enclosing the area closest to each point. This is known variously as a Voronoi mosaic, a Dirichlet tesselation, or Thiessen polygons.

Usage

tileplot(x, data = NULL, aspect = "iso",
         prepanel = "prepanel.default.xyplot",
         panel = "panel.voronoi", ...)

Arguments

x, data	formula and data as in levelplot, except that it expects irregularly spaced points rather than a regular grid.
aspect	aspect ratio: "iso" is recommended as it reproduces the distances used in the triangulation calculations.
panel, prepanel	see xyplot.
...	further arguments to the panel function, which defaults to panel.voronoi.

Details

See panel.voronoi for further options and details.

Author(s)

Felix Andrews [e-mail]

See Also

panel.voronoi, levelplot

Examples

xyz <- data.frame(x = rnorm(100), y = rnorm(100), z = rnorm(100))
tileplot(z ~ x * y, xyz)

## tripack is faster but non-free
## Not run: 
tileplot(z ~ x * y, xyz, use.tripack = TRUE)

## End(Not run)

## showing rectangular window boundary
tileplot(z ~ x * y, xyz, xlim = c(-2, 4), ylim = c(-2, 4))

## insert some missing values
xyz$z[1:10] <- NA
## the default na.rm = FALSE shows missing polygons
tileplot(z ~ x * y, xyz, border = "black",
  col.regions = grey.colors(100),
  pch = ifelse(is.na(xyz$z), 4, 21),
  panel = function(...) {
    panel.fill("hotpink")
    panel.voronoi(...)
  })
## use na.rm = TRUE to ignore points with missing values
update(trellis.last.object(), na.rm = TRUE)

## a quick and dirty approximation to US state boundaries
tmp <- state.center
tmp$Income <- state.x77[,"Income"]
tileplot(Income ~ x * y, tmp, border = "black",
  panel = function(x, y, ...) {
    panel.voronoi(x, y, ..., points = FALSE)
    panel.text(x, y, state.abb, cex = 0.6)
  })

Example output

Loading required package: lattice
Loading required package: RColorBrewer

     PLEASE NOTE:  The components "delsgs" and "summary" of the
 object returned by deldir() are now DATA FRAMES rather than
 matrices (as they were prior to release 0.0-18).
 See help("deldir").
 
     PLEASE NOTE: The process that deldir() uses for determining
 duplicated points has changed from that used in version
 0.0-9 of this package (and previously). See help("deldir").

latticeExtra documentation built on Sept. 19, 2020, 3:01 p.m.